Shitting on other people products with vague and inaccurate criticisms isn't a good deed, it's just bad form. People don't need you to "show them how to think for themselves." The other guy is right, either make a sound and specific criticism or don't say anything. You did exactly what he said, you made a bad argument which he refuted, then you moved the goal post so as not to appear wrong, while still leaving out the necessary detail to disprove your new vague claim, rather than admitting your mistake and making a better argument that included specifics about what is missing.